MTBE is not terribly toxic
- Thread starter y_p_w
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Originally Posted By: Shannow
How does Europe do it ?
They must be swimming in "coleman fuel".
Oh, and don't forget that cracking component...
They're working on it. E10 is now sold in several countries and most gasoline/petrol sold there now is E5. And given that the price of fuel is considerably higher there, they would have an incentive to just spend extra given the resistance to using more oxygenates, compared to the US which is far more price conscious.
There are of course other markets where the octane rating is typically really low and I suppose lower octane fuel streams could be "dumped".
How does Europe do it ?
They must be swimming in "coleman fuel".
Oh, and don't forget that cracking component...
They're working on it. E10 is now sold in several countries and most gasoline/petrol sold there now is E5. And given that the price of fuel is considerably higher there, they would have an incentive to just spend extra given the resistance to using more oxygenates, compared to the US which is far more price conscious.
There are of course other markets where the octane rating is typically really low and I suppose lower octane fuel streams could be "dumped".
Originally Posted By: y_p_w
They're working on it. E10 is now sold in several countries and most gasoline/petrol sold there now is E5. And given that the price of fuel is considerably higher there, they would have an incentive to just spend extra given the resistance to using more oxygenates, compared to the US which is far more price conscious.
You have to do better than that...tehy are going "green" for green's sake.
Not your premise that oxygenates are vital, and the basis for the "MTBE" isn't that bad, as it only makes water undrinkable.
Originally Posted By: y_p_w
There are of course other markets where the octane rating is typically really low and I suppose lower octane fuel streams could be "dumped".
Suppose...that's a term for don't know, and sill fixated on the "coleman fuel waste"
Oh, and again...you keep forgetting...
Originally Posted By: Shannow
Oh, and don't forget that cracking component...
Is it because you are shooting from the hip and really don't understand it ?
http://www.nrcan.gc.ca/energy/crude-petroleum/4561
Quote:
Refineries fall into three broad categories. The simplest is a topping plant, which consists only of a distillation unit and probably a catalytic reformer to provide octane. Yields from this plant would most closely reflect the natural yields from the crude processed. Typically only condensates or light sweet crude would be processed at this type of facility unless markets for heavy fuel oil (HFO) are readily and economically available. Asphalt plants are topping refineries that run heavy crude oil because they are only interested in producing asphalt.
The next level of refining is called a cracking refinery. This refinery takes the gas oil portion from the crude distillation unit (a stream heavier than diesel fuel, but lighter than HFO) and breaks it down further into gasoline and distillate components using catalysts, high temperature and/or pressure.
The last level of refining is the coking refinery. This refinery processes residual fuel, the heaviest material from the crude unit and thermally cracks it into lighter product in a coker or a hydrocraker. The addition of a fluid catalytic cracking unit (FCCU) or a hydro cracker significantly increases the yield of higher-valued products like gasoline and diesel oil from a barrel of crude, allowing a refinery to process cheaper, heavier crude while producing an equivalent or greater volume of high-valued products.
Hydrotreating is a process used to remove sulphur from finished products. As the requirement to produce ultra low sulphur products increases, additional hydrotreating capability is being added to refineries. Refineries that currently have large hydrotreating capability have the ability to process crude oil with a higher sulphur content.
Canada has primarily cracking refineries. These refineries run a mix of light and heavy crude oils to meet the product slate required by Canadian consumers. Historically, the abundance of domestically produced light sweet crude oils and a higher demand for distillate products, such as heating oil, than in some jurisdictions reduced the need for upgrading capacity in Canada.
i.e. you are fixated on the distillation limiting yield and having to "dump" the coleman fuel as you call it.
Cracking allows higher yields of high end products, and the "strawman" that you claim my pic to be is ACTUALLY what the market wants...jet fuel, diesel, heating oil, bitumen, petrocoke...the are all productes in their own right, all with a market.
You have still to demonstrate basic understanding, let alone WHY oxygenates are essential...
link us up with more than "suppose"
They're working on it. E10 is now sold in several countries and most gasoline/petrol sold there now is E5. And given that the price of fuel is considerably higher there, they would have an incentive to just spend extra given the resistance to using more oxygenates, compared to the US which is far more price conscious.
You have to do better than that...tehy are going "green" for green's sake.
Not your premise that oxygenates are vital, and the basis for the "MTBE" isn't that bad, as it only makes water undrinkable.
Originally Posted By: y_p_w
There are of course other markets where the octane rating is typically really low and I suppose lower octane fuel streams could be "dumped".
Suppose...that's a term for don't know, and sill fixated on the "coleman fuel waste"
Oh, and again...you keep forgetting...
Originally Posted By: Shannow
Oh, and don't forget that cracking component...
Is it because you are shooting from the hip and really don't understand it ?
http://www.nrcan.gc.ca/energy/crude-petroleum/4561
Quote:
Refineries fall into three broad categories. The simplest is a topping plant, which consists only of a distillation unit and probably a catalytic reformer to provide octane. Yields from this plant would most closely reflect the natural yields from the crude processed. Typically only condensates or light sweet crude would be processed at this type of facility unless markets for heavy fuel oil (HFO) are readily and economically available. Asphalt plants are topping refineries that run heavy crude oil because they are only interested in producing asphalt.
The next level of refining is called a cracking refinery. This refinery takes the gas oil portion from the crude distillation unit (a stream heavier than diesel fuel, but lighter than HFO) and breaks it down further into gasoline and distillate components using catalysts, high temperature and/or pressure.
The last level of refining is the coking refinery. This refinery processes residual fuel, the heaviest material from the crude unit and thermally cracks it into lighter product in a coker or a hydrocraker. The addition of a fluid catalytic cracking unit (FCCU) or a hydro cracker significantly increases the yield of higher-valued products like gasoline and diesel oil from a barrel of crude, allowing a refinery to process cheaper, heavier crude while producing an equivalent or greater volume of high-valued products.
Hydrotreating is a process used to remove sulphur from finished products. As the requirement to produce ultra low sulphur products increases, additional hydrotreating capability is being added to refineries. Refineries that currently have large hydrotreating capability have the ability to process crude oil with a higher sulphur content.
Canada has primarily cracking refineries. These refineries run a mix of light and heavy crude oils to meet the product slate required by Canadian consumers. Historically, the abundance of domestically produced light sweet crude oils and a higher demand for distillate products, such as heating oil, than in some jurisdictions reduced the need for upgrading capacity in Canada.
i.e. you are fixated on the distillation limiting yield and having to "dump" the coleman fuel as you call it.
Cracking allows higher yields of high end products, and the "strawman" that you claim my pic to be is ACTUALLY what the market wants...jet fuel, diesel, heating oil, bitumen, petrocoke...the are all productes in their own right, all with a market.
You have still to demonstrate basic understanding, let alone WHY oxygenates are essential...
link us up with more than "suppose"
Originally Posted By: Shannow
Not your premise that oxygenates are vital, and the basis for the "MTBE" isn't that bad, as it only makes water undrinkable.
Not vital if you mean that they would retool and spend more money making higher octane fuels without oxygenates. Sure supply could be met by other means. But using oxygenates is a cheap and easy way to boost the octane rating of fuel compared to almost any other means, and almost a no brainer given that ethanol is currently cheaper than gasoline. Certainly all new vehicles certified for sale in the United States have been designed with E10 compatibility for at least the last 30 years, but that may not be the case in other countries. The 1989 Integra I drove clearly stated up to 10% ethanol, 15% MTBE, and 5% methanol (with corrosion inhibitors) was compatible with its fuel system. And certainly American fuel producers would just keep on using ethanol (or MTBE) even without any of the renewable mandates. It could change in the future though, but right now there's a highly competitive marketplace in the US where few people would pay a steep premium for ethanol free fuel.
Quote:
The Shocking Truth About America's Ethanol Law: It Doesn't Matter (For Now)
http://www.npr.org/sections/thesalt/2016...-matter-for-now
I found two experts who've examined this question in great detail: Paul Niznik, an analyst at Stratas Advisors, an energy consulting business in Houston, and Scott Irwin, an economist who teaches at the University of Illinois. And here's their bottom line: If the law changed tomorrow and gasoline companies were free to ignore ethanol, they'd almost certainly keep right on blending ethanol into their fuel.
Got that? The ethanol mandate requires gasoline companies to do something that, at the moment, they'd do anyway.
The reason, in a word, is octane.
Octane is a measure of gasoline's tendency to ignite under pressure. If it's too low, the gasoline/air mixture in an engine's cylinders will burn too soon, creating damaging "knocking."
The industry standard for gasoline is 87. But getting gasoline's octane rating up to that standard costs money. It means more refining of the petroleum, or using high-octane compounds in your gasoline formula, such as — you guessed it — ethanol. So gasoline companies aren't using ethanol for its energy — they're buying it for its high octane rating.
There are other compounds that you can add to boost octane levels, but many, like alkylate or iso-octane, are generally more expensive than ethanol. Another additive that is widely used globally, called MTBE, has such a bad reputation for polluting the environment that many states have passed regulations that make it difficult to use.
"As of today, the alternative sources of octane are more expensive," says Irwin, who just updated his calculations on demand for ethanol last week.
Niznik, from Stratas Advisors, says that when corn prices hit a peak in 2012, because of a drought in the Midwest, there were bitter complaints about the ethanol mandate among farmers and people in the food industry who wanted that corn to be used for animal feed. "They were assuming that if we used less ethanol, the price of corn would go down," he says.
"The truth is," Niznik continues, "the [petroleum] refining folks knew in their hearts that if the [ethanol mandate] went away for a while, ethanol use wouldn't drop much. They were looking around at the octane replacements, and knew that those things were really expensive." Niznik says removing ethanol also would have forced gasoline companies to disrupt their refinery operations.
** ** **
According to Niznik, there may be some justification for that fear. "Refiners are looking strategically up the road," he says. "They're looking at forecasts of shrinking gasoline demand. They could say to themselves, 'Why should I be giving 10 percent away? I want to sell product that's mine!' "
Switching to petroleum-based octane boosters such as alkylate would not be easy, though. In the short term, Niznik says, it would be self-defeating. Oil companies are competing against each other to make cheap gas, and "the guy with ethanol is probably going to win."
But those other sources of octane are getting cheaper, Niznik says, and in the long run, they might be just as cheap as ethanol. In 10 years, he says, the business case for using ethanol could disappear.
And yes the primary reason why MTBE has been mostly phased out in the US is the affect on the taste of drinking water.
Not your premise that oxygenates are vital, and the basis for the "MTBE" isn't that bad, as it only makes water undrinkable.
Not vital if you mean that they would retool and spend more money making higher octane fuels without oxygenates. Sure supply could be met by other means. But using oxygenates is a cheap and easy way to boost the octane rating of fuel compared to almost any other means, and almost a no brainer given that ethanol is currently cheaper than gasoline. Certainly all new vehicles certified for sale in the United States have been designed with E10 compatibility for at least the last 30 years, but that may not be the case in other countries. The 1989 Integra I drove clearly stated up to 10% ethanol, 15% MTBE, and 5% methanol (with corrosion inhibitors) was compatible with its fuel system. And certainly American fuel producers would just keep on using ethanol (or MTBE) even without any of the renewable mandates. It could change in the future though, but right now there's a highly competitive marketplace in the US where few people would pay a steep premium for ethanol free fuel.
Quote:
The Shocking Truth About America's Ethanol Law: It Doesn't Matter (For Now)
http://www.npr.org/sections/thesalt/2016...-matter-for-now
I found two experts who've examined this question in great detail: Paul Niznik, an analyst at Stratas Advisors, an energy consulting business in Houston, and Scott Irwin, an economist who teaches at the University of Illinois. And here's their bottom line: If the law changed tomorrow and gasoline companies were free to ignore ethanol, they'd almost certainly keep right on blending ethanol into their fuel.
Got that? The ethanol mandate requires gasoline companies to do something that, at the moment, they'd do anyway.
The reason, in a word, is octane.
Octane is a measure of gasoline's tendency to ignite under pressure. If it's too low, the gasoline/air mixture in an engine's cylinders will burn too soon, creating damaging "knocking."
The industry standard for gasoline is 87. But getting gasoline's octane rating up to that standard costs money. It means more refining of the petroleum, or using high-octane compounds in your gasoline formula, such as — you guessed it — ethanol. So gasoline companies aren't using ethanol for its energy — they're buying it for its high octane rating.
There are other compounds that you can add to boost octane levels, but many, like alkylate or iso-octane, are generally more expensive than ethanol. Another additive that is widely used globally, called MTBE, has such a bad reputation for polluting the environment that many states have passed regulations that make it difficult to use.
"As of today, the alternative sources of octane are more expensive," says Irwin, who just updated his calculations on demand for ethanol last week.
Niznik, from Stratas Advisors, says that when corn prices hit a peak in 2012, because of a drought in the Midwest, there were bitter complaints about the ethanol mandate among farmers and people in the food industry who wanted that corn to be used for animal feed. "They were assuming that if we used less ethanol, the price of corn would go down," he says.
"The truth is," Niznik continues, "the [petroleum] refining folks knew in their hearts that if the [ethanol mandate] went away for a while, ethanol use wouldn't drop much. They were looking around at the octane replacements, and knew that those things were really expensive." Niznik says removing ethanol also would have forced gasoline companies to disrupt their refinery operations.
** ** **
According to Niznik, there may be some justification for that fear. "Refiners are looking strategically up the road," he says. "They're looking at forecasts of shrinking gasoline demand. They could say to themselves, 'Why should I be giving 10 percent away? I want to sell product that's mine!' "
Switching to petroleum-based octane boosters such as alkylate would not be easy, though. In the short term, Niznik says, it would be self-defeating. Oil companies are competing against each other to make cheap gas, and "the guy with ethanol is probably going to win."
But those other sources of octane are getting cheaper, Niznik says, and in the long run, they might be just as cheap as ethanol. In 10 years, he says, the business case for using ethanol could disappear.
And yes the primary reason why MTBE has been mostly phased out in the US is the affect on the taste of drinking water.
Originally Posted By: Shannow
MTBE is also slower to degrade when it DOES get into the environment.
Hands up everyone in the thread who wants their water to taste like turpentine, even if it's minimal risk ?
If it did, what would you expect to be done about it ?
Hands up who doesn't care if their neighbour's water tastes like turpentine...after all it's not going to hurt them ?
The town where I went to college drew its water from a 25-mile long aquifer. I became quite familiar with the whole operation as a chemistry major whose research advisor/favorite professor(just talked to him yesterday) was on the town water board.
In any case, back in the early 1990s a gas station had a fuel tank rupture and contaminate the spring used for water.
At the time, it effectively shut down the down for a month-the college closed and several business did as well.
In that time, they did two things to solve it. One was build a pipeline to the neighboring town(my home town) which has excess purifying capacity so could supply it when needed.
The second thing was to build two large aeration towers. Those are still used(I think some is still seeping a bit even now). The aeration towers basically just blast the water with a ton of air as it's falling over baffles-the idea is that it drives off any volatiles in it.
Also of note is that the treatment plant analyzes total organic carbon(TOC) on-site every day. I think that the EPA requirements are that it only be done monthly, or at least infrequently enough that it's unusual for anyone outside a large municipal system to even have the TOC instrument. The gasoline issue still haunts them, though, and they are extremely diligent about making sure they deliver a safe and good-tasting product.
MTBE is also slower to degrade when it DOES get into the environment.
Hands up everyone in the thread who wants their water to taste like turpentine, even if it's minimal risk ?
If it did, what would you expect to be done about it ?
Hands up who doesn't care if their neighbour's water tastes like turpentine...after all it's not going to hurt them ?
The town where I went to college drew its water from a 25-mile long aquifer. I became quite familiar with the whole operation as a chemistry major whose research advisor/favorite professor(just talked to him yesterday) was on the town water board.
In any case, back in the early 1990s a gas station had a fuel tank rupture and contaminate the spring used for water.
At the time, it effectively shut down the down for a month-the college closed and several business did as well.
In that time, they did two things to solve it. One was build a pipeline to the neighboring town(my home town) which has excess purifying capacity so could supply it when needed.
The second thing was to build two large aeration towers. Those are still used(I think some is still seeping a bit even now). The aeration towers basically just blast the water with a ton of air as it's falling over baffles-the idea is that it drives off any volatiles in it.
Also of note is that the treatment plant analyzes total organic carbon(TOC) on-site every day. I think that the EPA requirements are that it only be done monthly, or at least infrequently enough that it's unusual for anyone outside a large municipal system to even have the TOC instrument. The gasoline issue still haunts them, though, and they are extremely diligent about making sure they deliver a safe and good-tasting product.
Originally Posted By: bunnspecial
Originally Posted By: Shannow
MTBE is also slower to degrade when it DOES get into the environment.
Hands up everyone in the thread who wants their water to taste like turpentine, even if it's minimal risk ?
If it did, what would you expect to be done about it ?
Hands up who doesn't care if their neighbour's water tastes like turpentine...after all it's not going to hurt them ?
The town where I went to college drew its water from a 25-mile long aquifer. I became quite familiar with the whole operation as a chemistry major whose research advisor/favorite professor(just talked to him yesterday) was on the town water board.
In any case, back in the early 1990s a gas station had a fuel tank rupture and contaminate the spring used for water.
At the time, it effectively shut down the down for a month-the college closed and several business did as well.
In that time, they did two things to solve it. One was build a pipeline to the neighboring town(my home town) which has excess purifying capacity so could supply it when needed.
The second thing was to build two large aeration towers. Those are still used(I think some is still seeping a bit even now). The aeration towers basically just blast the water with a ton of air as it's falling over baffles-the idea is that it drives off any volatiles in it.
Also of note is that the treatment plant analyzes total organic carbon(TOC) on-site every day. I think that the EPA requirements are that it only be done monthly, or at least infrequently enough that it's unusual for anyone outside a large municipal system to even have the TOC instrument. The gasoline issue still haunts them, though, and they are extremely diligent about making sure they deliver a safe and good-tasting product.
I thought that activated carbon filtration would remove MTBE if the water is kept in contact long enough. So a Brita filter might not do it, but a system designed to slow down the flow rate might. I know it gets very expensive to do that on a municipal water delivery scale, but may not be at the home when just preparing drinking water. It's not like it's cost effective to use reverse osmosis on water that's mostly going to be used to flush toilets, wash dishes, or water lawns.
I've dealt with well water at one place where I lived. Our water rates were extremely low, but the water was absolutely foul tasting. It was weird too - slightly yellow where aerated water would have little bubbles that stayed around for minutes, and an off odor that could be easily smelled with a strange taste. The water quality reports noted the extremely high magnesium/calcium content, which I verified this with an fish aquarium test kit. But no discrenable MTBE. However, from that experience I understand why the taste of water is considered important.
Originally Posted By: Shannow
MTBE is also slower to degrade when it DOES get into the environment.
Hands up everyone in the thread who wants their water to taste like turpentine, even if it's minimal risk ?
If it did, what would you expect to be done about it ?
Hands up who doesn't care if their neighbour's water tastes like turpentine...after all it's not going to hurt them ?
The town where I went to college drew its water from a 25-mile long aquifer. I became quite familiar with the whole operation as a chemistry major whose research advisor/favorite professor(just talked to him yesterday) was on the town water board.
In any case, back in the early 1990s a gas station had a fuel tank rupture and contaminate the spring used for water.
At the time, it effectively shut down the down for a month-the college closed and several business did as well.
In that time, they did two things to solve it. One was build a pipeline to the neighboring town(my home town) which has excess purifying capacity so could supply it when needed.
The second thing was to build two large aeration towers. Those are still used(I think some is still seeping a bit even now). The aeration towers basically just blast the water with a ton of air as it's falling over baffles-the idea is that it drives off any volatiles in it.
Also of note is that the treatment plant analyzes total organic carbon(TOC) on-site every day. I think that the EPA requirements are that it only be done monthly, or at least infrequently enough that it's unusual for anyone outside a large municipal system to even have the TOC instrument. The gasoline issue still haunts them, though, and they are extremely diligent about making sure they deliver a safe and good-tasting product.
I thought that activated carbon filtration would remove MTBE if the water is kept in contact long enough. So a Brita filter might not do it, but a system designed to slow down the flow rate might. I know it gets very expensive to do that on a municipal water delivery scale, but may not be at the home when just preparing drinking water. It's not like it's cost effective to use reverse osmosis on water that's mostly going to be used to flush toilets, wash dishes, or water lawns.
I've dealt with well water at one place where I lived. Our water rates were extremely low, but the water was absolutely foul tasting. It was weird too - slightly yellow where aerated water would have little bubbles that stayed around for minutes, and an off odor that could be easily smelled with a strange taste. The water quality reports noted the extremely high magnesium/calcium content, which I verified this with an fish aquarium test kit. But no discrenable MTBE. However, from that experience I understand why the taste of water is considered important.
Originally Posted By: Shannow
Originally Posted By: y_p_w
I understand why the taste of water is considered important.
It IS important, full stop.
Basic quality of life issue, and you've got no right to impact on others...pure and simple.
But the presence of MTBE in water supplies is something that can be addressed by removing it. I've dealt with bad drinking water before - the one from local wells that I mentioned. No matter how bad it tasted, how it caused crusty deposits everywhere, how it looked out of the faucet - the water agency wasn't going to do anything to address "aesthetic" effects until "safe" drinking water standards were breached. And in line with how this topic has progressed, it was primarily about how much it was going to cost and how difficult it would be to replace this cheap water source. And here in California once a municipality has a reliable water supply, they fight like crazy to keep it. San Francisco has a highly controversial source within Yosemite National Park, and there has been a decades long fight to tear down the O'Shaughnessy Dam. San Francisco wants to keep it because it's so pristine that they aren't required to do anything more than minimally process it. Opponents claim that there's dam capacity further down that can easily impound the same amount of water.
My main intent on starting this thread wasn't about ethanol, oxygenates, or octane rating, but to respond to a post in a locked topic that claimed that MTBE was discontinued in the United States because of concerns of toxicity in drinking water.
Originally Posted By: y_p_w
I understand why the taste of water is considered important.
It IS important, full stop.
Basic quality of life issue, and you've got no right to impact on others...pure and simple.
But the presence of MTBE in water supplies is something that can be addressed by removing it. I've dealt with bad drinking water before - the one from local wells that I mentioned. No matter how bad it tasted, how it caused crusty deposits everywhere, how it looked out of the faucet - the water agency wasn't going to do anything to address "aesthetic" effects until "safe" drinking water standards were breached. And in line with how this topic has progressed, it was primarily about how much it was going to cost and how difficult it would be to replace this cheap water source. And here in California once a municipality has a reliable water supply, they fight like crazy to keep it. San Francisco has a highly controversial source within Yosemite National Park, and there has been a decades long fight to tear down the O'Shaughnessy Dam. San Francisco wants to keep it because it's so pristine that they aren't required to do anything more than minimally process it. Opponents claim that there's dam capacity further down that can easily impound the same amount of water.
My main intent on starting this thread wasn't about ethanol, oxygenates, or octane rating, but to respond to a post in a locked topic that claimed that MTBE was discontinued in the United States because of concerns of toxicity in drinking water.
Originally Posted By: y_p_w
Originally Posted By: bunnspecial
Originally Posted By: Shannow
MTBE is also slower to degrade when it DOES get into the environment.
Hands up everyone in the thread who wants their water to taste like turpentine, even if it's minimal risk ?
If it did, what would you expect to be done about it ?
Hands up who doesn't care if their neighbour's water tastes like turpentine...after all it's not going to hurt them ?
The town where I went to college drew its water from a 25-mile long aquifer. I became quite familiar with the whole operation as a chemistry major whose research advisor/favorite professor(just talked to him yesterday) was on the town water board.
In any case, back in the early 1990s a gas station had a fuel tank rupture and contaminate the spring used for water.
At the time, it effectively shut down the down for a month-the college closed and several business did as well.
In that time, they did two things to solve it. One was build a pipeline to the neighboring town(my home town) which has excess purifying capacity so could supply it when needed.
The second thing was to build two large aeration towers. Those are still used(I think some is still seeping a bit even now). The aeration towers basically just blast the water with a ton of air as it's falling over baffles-the idea is that it drives off any volatiles in it.
Also of note is that the treatment plant analyzes total organic carbon(TOC) on-site every day. I think that the EPA requirements are that it only be done monthly, or at least infrequently enough that it's unusual for anyone outside a large municipal system to even have the TOC instrument. The gasoline issue still haunts them, though, and they are extremely diligent about making sure they deliver a safe and good-tasting product.
I thought that activated carbon filtration would remove MTBE if the water is kept in contact long enough. So a Brita filter might not do it, but a system designed to slow down the flow rate might. I know it gets very expensive to do that on a municipal water delivery scale, but may not be at the home when just preparing drinking water. It's not like it's cost effective to use reverse osmosis on water that's mostly going to be used to flush toilets, wash dishes, or water lawns.
This plant DOES use carbon filtration. I'm working from memory, but there were two beds side-by side that had a layer of sand and then a layer of finely ground Pennsylvania Anthracite. I want to say that each filtration bed was about 15' square and probably 20 ft tall. They would alternate between the two, and I seem to remember that they were changed every 6 months or so.
Again, working from memory, I think the filter beds were close to the "last pass." The water was drawn off the clarifier, went through the aeration towers I mentioned, and then passed through the filter beds before it was treated with chloramines before going out into the final system. The clarifier gets MOST of the solids out, and then the aerators get the volatiles out. The main purpose of the filter bed is just as sort of a last-pass clean up before the water bed went out.
In fact, this particular plant actually had a fish tank next to the control panel that looked out over the filter bed. The tank had pre-filtered water flowing through it, and it served two purposes. One was so that they could see the turbidity before going into the filters, and the other was as an early toxicity warning(if the fish die, you'd better start checking on things).
Originally Posted By: bunnspecial
Originally Posted By: Shannow
MTBE is also slower to degrade when it DOES get into the environment.
Hands up everyone in the thread who wants their water to taste like turpentine, even if it's minimal risk ?
If it did, what would you expect to be done about it ?
Hands up who doesn't care if their neighbour's water tastes like turpentine...after all it's not going to hurt them ?
The town where I went to college drew its water from a 25-mile long aquifer. I became quite familiar with the whole operation as a chemistry major whose research advisor/favorite professor(just talked to him yesterday) was on the town water board.
In any case, back in the early 1990s a gas station had a fuel tank rupture and contaminate the spring used for water.
At the time, it effectively shut down the down for a month-the college closed and several business did as well.
In that time, they did two things to solve it. One was build a pipeline to the neighboring town(my home town) which has excess purifying capacity so could supply it when needed.
The second thing was to build two large aeration towers. Those are still used(I think some is still seeping a bit even now). The aeration towers basically just blast the water with a ton of air as it's falling over baffles-the idea is that it drives off any volatiles in it.
Also of note is that the treatment plant analyzes total organic carbon(TOC) on-site every day. I think that the EPA requirements are that it only be done monthly, or at least infrequently enough that it's unusual for anyone outside a large municipal system to even have the TOC instrument. The gasoline issue still haunts them, though, and they are extremely diligent about making sure they deliver a safe and good-tasting product.
I thought that activated carbon filtration would remove MTBE if the water is kept in contact long enough. So a Brita filter might not do it, but a system designed to slow down the flow rate might. I know it gets very expensive to do that on a municipal water delivery scale, but may not be at the home when just preparing drinking water. It's not like it's cost effective to use reverse osmosis on water that's mostly going to be used to flush toilets, wash dishes, or water lawns.
This plant DOES use carbon filtration. I'm working from memory, but there were two beds side-by side that had a layer of sand and then a layer of finely ground Pennsylvania Anthracite. I want to say that each filtration bed was about 15' square and probably 20 ft tall. They would alternate between the two, and I seem to remember that they were changed every 6 months or so.
Again, working from memory, I think the filter beds were close to the "last pass." The water was drawn off the clarifier, went through the aeration towers I mentioned, and then passed through the filter beds before it was treated with chloramines before going out into the final system. The clarifier gets MOST of the solids out, and then the aerators get the volatiles out. The main purpose of the filter bed is just as sort of a last-pass clean up before the water bed went out.
In fact, this particular plant actually had a fish tank next to the control panel that looked out over the filter bed. The tank had pre-filtered water flowing through it, and it served two purposes. One was so that they could see the turbidity before going into the filters, and the other was as an early toxicity warning(if the fish die, you'd better start checking on things).
Originally Posted By: bunnspecial
This plant DOES use carbon filtration. I'm working from memory, but there were two beds side-by side that had a layer of sand and then a layer of finely ground Pennsylvania Anthracite. I want to say that each filtration bed was about 15' square and probably 20 ft tall. They would alternate between the two, and I seem to remember that they were changed every 6 months or so.
I thought how fast the water goes through affects how effective the filtration of certain substances will be. I know chloramine isn't something that would be taken out of a municipal water supply, but supposedly many home filters don't specify that they remove chloramine because they don't necessarily give enough time for water to have enough "dwell time" with the carbon. Some of the systems I looked into said that they could claim that they could remove chloramine because they used some sort of labyrinth system to extend the contact of the water with the carbon. It looks like meeting NSF Standard 53 can be used to claim that MTBE is removed as a volatile organic compound.
This plant DOES use carbon filtration. I'm working from memory, but there were two beds side-by side that had a layer of sand and then a layer of finely ground Pennsylvania Anthracite. I want to say that each filtration bed was about 15' square and probably 20 ft tall. They would alternate between the two, and I seem to remember that they were changed every 6 months or so.
I thought how fast the water goes through affects how effective the filtration of certain substances will be. I know chloramine isn't something that would be taken out of a municipal water supply, but supposedly many home filters don't specify that they remove chloramine because they don't necessarily give enough time for water to have enough "dwell time" with the carbon. Some of the systems I looked into said that they could claim that they could remove chloramine because they used some sort of labyrinth system to extend the contact of the water with the carbon. It looks like meeting NSF Standard 53 can be used to claim that MTBE is removed as a volatile organic compound.
Originally Posted By: Shannow
Being able to filter it out doesn't justify letting it get there in the first place.
It's simply not necessary in the fuel supply.
We have a lot of things in life that got there even though it seem bad in hindsight. Things like cocaine in patent medicine or TEL in gasoline.
I'm not arguing that MTBE ending up in water is a good thing or acceptable. I'm just saying that the MTBE scare was overblown as a health risk. And for various reasons of cost, need, and existing infrastructure, ethanol would still be used in the vast majority of gasoline in the United States for the next decade at least.
Being able to filter it out doesn't justify letting it get there in the first place.
It's simply not necessary in the fuel supply.
We have a lot of things in life that got there even though it seem bad in hindsight. Things like cocaine in patent medicine or TEL in gasoline.
I'm not arguing that MTBE ending up in water is a good thing or acceptable. I'm just saying that the MTBE scare was overblown as a health risk. And for various reasons of cost, need, and existing infrastructure, ethanol would still be used in the vast majority of gasoline in the United States for the next decade at least.
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